1. Field of invention
The invention relates to trailers suitable for transporting harvester headers.
2. Background
As self-propelled harvesting machines get larger to cater for the demands of modern farmers, the headers become wider too. It is well known to detach the header of, say, a combine harvester when moving from field to field, especially when travelling on roads is required, due to the excessive width. For the transport operation, a dedicated header trailer is typically employed to carry the header lengthwise.
FIG. 1 schematically represents a combine harvester 10 towing a header trailer 12 on top of which is shown the detached harvester header 14. Although shown as being towed by a combine 10 it will be appreciated that the header trailer may be towed by any suitable vehicle, most commonly an agricultural tractor.
The example header trailer 12 shown includes a chassis 16 with a front towing hitch 18 for attachment to the towing vehicle 10 and a rear axle assembly 20 which supports a pair of rear wheels 22. A front axle assembly 24 comprises a pony truck which is provided to support one or more front wheels 26. The provision of one or more front wheels 26 maintains the chassis 16 at a constant level to ease attachment and detachment of the header 14 from the feeder house 28 of combine 10. Furthermore, the provision of front pony truck reduces the vertical load on the front hitch 18 thus placing less strain on primitive towing hitches often provided at the rear of combine harvesters.
Harvester headers today can reach operating widths of up to 15 meters which require long header trailers in the region of 18 meters in length. The lengths involved can make manoeuvrability and particularly tight turns troublesome because the rear wheels 22 of the header trailer 12 take the shortest route when following the towing machine.